This invention pertains to the art of vacuum cleaner devices and more particularly to motor and drive assemblies.
The invention is particularly applicable as an electrically insulating belt drive for vacuum cleaners having a rotating brush powered by a belt running from the motor shaft to the brush.
Various forms and types of belt drives are known in the vacuum cleaner industry. Most use an elastomeric belt driven by an electric motor that also powers a fan to create the vacuum necessary for suction cleaning U.S. Pat. No. 4,633,543 shows such an arrangement where a motor shaft extension is used as a belt drive.
Frequently, it is necessary to access the belt either for replacement or for removal in those situations where a separate suction hose may be attached to the cleaner as an accessory tool. In the above cited patent, the vacuum cleaner housing includes an opening which is intended to be readily accessible to a user of the cleaner to allow attachment of the tool. Such attachment requires removal of the belt from the belt drive. If the belt is subsequently reattached by hand, without use of a special belt attachment tool, the operator's hands may contact the belt drive. The shaft extension comprising the belt drive is one insulation layer away from electrical communication with the motor. There is electrical insulation between the motor shaft and the armature. Accordingly, for safety reasons it has been desired that a system be provided in which the shaft extension is doubly electrically insulated from the motor to prevent electrical shock to an operator.
More importantly, current safety standards suggest that a consumer appliance of this type should be so doubly-insulated, that is, that at least two layers of insulation should exist between the motor and the user. With a metallic belt drive only a single layer exists between the motor shaft and the armature.
The shaft extension has normally been metallic due to operating requirements of heavy loads and high temperatures as a part of its normal use. Substitution of a mere plastic material for a metal belt drive has proved unsuccessful since most plastic materials are unable to withstand the loads and heat and those that are, are not cost acceptable as part of the product.
The present invention contemplates a new and improved shaft extension for a vacuum cleaner motor which overcomes the above-identified problems and others to provide a new belt drive which is simple in design, economical to manufacture and which sufficiently electrically insulates the motor from an operator to avoid unsafe exposure to potential electrical shock problems.